1. Field of the Invention
This invention relates to a method for the production of an easily polymerizable substance and a purification apparatus to be used therein. More specifically, it relates to a method for the purification of an easily polymerizable substance and a purification apparatus to be used therein and a method for the prevention of an easily polymerizable substance from yielding to polymerization in a distillation column and a purification apparatus to be used therein.
2. Description of the Related Art
Since easily polymerizable substances such as acrylic acid and methacrylic acid are liable to polymerize, they are purified in the presence of a polymerization inhibitor.
When such an easily polymerizable substance is distilled, for example, it stagnates in a liquid state on the inner surfaces of structural members of a distillation device and, as such, inevitably succumbs to polymerization. To avoid this phenomenon, this polymer has been separated by passing through a strainer the liquid withdrawn from the distillation device. Alternatively, the fact that stopping the operation of the distillation device and then artificially removing the polymer accumulated inside the device has been resorted.
As one measure to eliminate such a problem as mentioned above, JP-A-10-212,249 describes the idea of preventing an easily polymerizable organic compound from stagnating in a purification device by providing liquid passing openings to the tray supporting member or the packing supporting member of the device.
FIG. 1 is a diagram that depicts the conventional method for fixing a tray to a support ring by the use of horizontal clamps. In FIG. 1, a tray 1 is fixed to a support ring 2 with a horizontal clamp 7, washer 5, nut 4, and bolt 6. Incidentally, the support ring 2 is fixed to the inner wall 3 of a distillation column. FIG. 2 is a diagram for illustrating the horizontal clamp used in FIG. 1. FIG. 2A is a plan view of a horizontal clamp 27, FIG. 2B a front view thereof, and FIG. 2C a side view thereof. The term “horizontal clamp” as used herein, as is clear from FIG. 2A, refers to the width of the horizontal part of the clamp which exceeds 1.5 times the axial diameter of the bolt.
FIG. 3 is a diagram that depicts the conventional liquid passing openings formed in the support ring, which is fixed to the inner wall of the distillation column. With reference to FIG. 3 which is a diagram of the column as viewed from above, the liquid substance stagnating on a support ring 32 fixed to an inner wall 33 of the distillation column falls down via liquid passing openings 38.
According to this measure, the easily polymerizable organic compound is allowed to pass through the liquid passing openings, so that the stagnation can be lessened and the polymerization can be decreased to a certain extent. It, however, is not fully satisfied.